Electron Paramagnetic Resonance in Biology: Spin Trapping

Abstract

Discovered in 1945 by Zavoisky1, electron paramagnetic resonance (EPR) has since been applied to a large number of research areas. It is a spectroscopic method using frequencies in the microwave region (i.e. 109 up to 1011hz) and wavelengths from approximately 10−3 to 10−1 meters; it is limited to the detection of unpaired electrons. Unpaired electrons are present in free radicals, triplet electronic states and transition and rare earth ions. The sensitivity of the method allows radical concentrations of 10 nM to be detected.